USGS PCMSC

Permanent Displacement Response Spectra

Index Back to home page About these web pages Conclusions Slope strength Motion studies Field parameters Compliance Abstract Field Parameters.

Critical field parameters in compliant dynamic displacement analysis:

(a) Shear wave velocity measurements characterize soil stiffness and resonance
Photo of SASW equipment.
Photo of SASW set up in the field. Photo of man operating a wacker as a sound source.
Shear wave velocity profiles are determined by the Spectral Analysis of Surface Waves (SASW) method. Field motion data are collected and a Rayleigh wave dispersion curve is computed. The shear wave profile is computed by forward inversion.
Rayleigh wave dispersion curve. Vs (SASW)

(b) Soil yielding stress is determined by shearing the soil. For clay deposits we use a large self-boring vane apparatus that sounds to 10 meters.
Site map of SASW locations around the San Francisco Bay Area. Graph of shear resistance. We visited sites throughout San Francisco Bay to measure the shear resistance of soft Bay Mud. We found that the effective stress normalized shear strength properties are similar, regardless of location.
Shear strength plot in San Francisco Bay mud. Click on figures to view larger image (32K) (16K).

geotech/spectraposter/field.html
contact: Robert Kayen
last modified 2019